Normal Conditions

(1) The conditions of use of measurement equipment under which the influential factors, such as temperature and supply voltage, have normal (specified) values or are within the limits of the permissible deviations from these values. The normal conditions are indicated on the scales of measurement equipment, in standards for such equipment, in technical descriptions, and in instruction manuals. The limits of the permissible fundamental errors of measurement equipment are specified for normal conditions. The following values are often adopted as the normal conditions for electrical measuring instruments: temperature, within a range of 20° ± 2°C; supply voltage, as indicated on the scale, ± 2 percent; frequency, 49–51 hertz.

(2) The physical conditions defined by pressure p = 101,325 newtons per sq m (N/m²) = 760 mm Hg (normal atmosphere) and a temperature of 273.15°K (0°C), at which the molar volume of an ideal gas V₀ = 2.24136 × 10^–2m³/mole. The normal acceleration of free fall is assumed to be equal to g_n = 9.80665 m/sec².